We are engaged in the first systematic efforts to exploit hydrogenation in C-C couplings beyond hydroformylation. Using cationic rhodium and iridium catalysts, we have found that diverse ?-unsaturated reactants reductively couple to carbonyl compounds and imines under hydrogenation conditions, offering a byproduct-free alternative to stoichiometric organometallics in a range of classical C=X (X = O, NR) addition processes. This concept is extended further via C-C bond forming transfer hydrogenation. Here, using ruthenium or iridium catalysts, alcohols serve dually as hydrogen donors and aldehyde precursors, enabling carbonyl addition directly from the alcohol oxidation level in the absence of stoichiometric byproducts. In the proposed funding period, byproduct-free C-C couplings of alcohol and amines with abundant, renewable feedstocks will be developed, including the first hydrogen-mediated Grignard additions of organic halides. Other areas of investigation include redox neutral couplings of ?-olefins to carbonyl partners, and initial explorations into the use of iron-based catalysts for transfer hydrogenative coupling.